Double DC-DC converter for uninterruptible power supply applications

This paper presents a double DC-DC converter for uninterruptible power supply applications. The converter has a simple structure and is applied to a high capacity uninterruptible power supply (UPS). In comparison with a conventional DC-DC converter, a double DC-DC converter exhibits lower ripple current and offers many benefits to UPS systems such as size/weight reduction and higher efficiency. The double DC-DC converter was implemented in a transformerless three-level UPS with capacity of 750kVA, rated at a nominal input/output voltage of 480V. Test results confirm the excellent transient performance of the proposed equipment as well as the high DC-DC-AC efficiency (about 97%) during the discharging mode. The overall design of the proposed UPS aims to contribute to greening critical facilities such as information technology (IT) systems by delivering high reliability and high efficiency in a compact footprint.